1. Field of the Invention
Apparatuses and methods consistent with the present invention relate to a plasma display panel (PDP), and more particularly, to a plasma display panel that prevents low discharge at low temperature.
2. Description of the Related Art
In general, a plasma display panel (PDP), which is a picture display device using electric discharge, has high luminance and wide visible angle and thus is widely used as a flat panel display. The plasma display panel emits visible rays by injecting gases between two substrates having electrodes thereon, discharging the gases between the electrodes by applying a direct-current (DC) voltage or an alternate-current (AC) voltage, and exciting phosphors using ultraviolet (UV) rays generated by the discharged gases.
A plasma display panel is classified into a DC type and an AC type according to the discharge type. The DC type plasma display panel is constructed such that all electrodes are exposed to a discharge space and thus a migration of charges directly occurs between the corresponding electrodes. On the other hand, the AC type plasma display panel is constructed such that at least one electrode is covered by a dielectric layer, and there is no direct migration of charges between the corresponding electrodes. Instead, ions and electrons produced by the discharge adhere to the surface of the dielectric layer to form wall charges.
Also, a plasma display panel is classified into an opposite discharge type and a surface discharge type according to the type of arrangement of electrodes. In the opposite discharge plasma display panel, a pair of sustaining electrodes are disposed on a front substrate and a rear substrate, respectively, and a discharge occurs in a direction of a vertical axis of the panel. On the other hand, in the surface discharge plasma display panel, a pair of sustaining substrates are disposed on the same substrate, and a discharge occurs on a flat surface of the substrate.
The opposite discharge plasma display panel has high luminous efficiency but a phosphor layer is easily degraded by plasma and a discharge requires high voltage. For this reason, the surface discharge plasma display panel has been generally used.
FIGS. 1 and 2 illustrate a conventional AC type plasma display panel. FIG. 2 illustrates a sectional structure of the plasma display panel of FIG. 1, in which a front substrate is rotated by 90°.
Referring to FIGS. 1 and 2, the conventional AC type plasma display panel has a rear substrate 10 and a front substrate 20.
A plurality of stripe-shaped address electrodes 11 are formed on a top surface of the rear substrate 10 and are covered by a first dielectric layer 12. A plurality of partitions 13 are formed on the first dielectric layer 12 to be spaced a predetermined distance apart from each other in order to prevent electric and optical crosstalk between discharge cells 14. Red (R), green (G), and blue (B) phosphor layers 15 are formed to a predetermined thickness on an inner surface of the discharge cells 14 defined by the partitions 13. A discharge gas containing one selected from Ne, Xe, and a gas mixture thereof is injected into the discharge cells 14.
The front substrate 20 is a transparent substrate generally formed of glass, through which visible rays can pass, and is combined with the rear substrate 10 on which the partitions 13 are formed. Stripe-shaped sustaining electrodes 21a and 21b are formed on a bottom surface of the front substrate 20 perpendicular to the address electrodes 11. The sustaining electrodes 21a and 21b are formed of a transparent transmission material, such as indium tin oxide (ITO), so as to increase optical transmitivity. Also, bus electrodes 22a and 22b, formed of metal, are formed on bottom surfaces of the sustaining electrodes 21a and 21b, respectively, to have a smaller width than the sustaining electrodes 21a and 21b to reduce line resistances of the sustaining electrodes 21a and 21b. The sustaining electrodes 21a and 21b and the bus electrodes 22a and 22b are covered by a second dielectric layer 23, and a protective layer 24 is formed on a bottom surface of the second dielectric layer 23. The protective layer 24, such as a MgO layer, prevents damage of the second dielectric layer 23 due to plasma sputtering and emits secondary electrons to reduce discharge voltage and sustaining voltage.
An operating timing of the conventional plasma display panel comprises a resetting period, an addressing period, and a sustaining period. In the resetting period, a charge state of all of the discharge cells is initialized to allow efficient addressing of the discharge cells 14. In the addressing period, an address discharge occurs between the address electrode 11 and one sustaining electrode 21b (i.e., a Y electrode) in a selected discharge cell 14, thereby accumulating wall charges. In the sustaining period, a sustaining discharge occurs between the Y electrode 21b and another sustaining electrode 21a (i.e., an X electrode) in the discharge cell 14 including the wall charges. In the sustaining period, the phosphor layer 15 of the discharge cell 14 is excited using ultraviolet rays generated by discharge gases, to allow the plasma display panel to emit visible rays. The visible rays are radiated through the front substrate 20 to form images recognized by a user.
The yield of plasma display panels is determined by the uniform discharge characteristic of panels and greatly affects the panels' cost. In the conventional plasma display panel, the protective layer 24 is formed by depositing MgO. However, if the protective layer 24 is formed of MgO, low discharge occurs at a low temperature of 0° C. or less.